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--- dosimetry:userguide:dose_calculation_functions:dcf [2015/07/02 16:19] – dpatenaude
+++ dosimetry:userguide:dose_calculation_functions:dcf [2021/07/29 18:28] (current) – external edit 127.0.0.1
@@ Line 2: / Line 2: @@
 Dose Calculation Functions rely heavily on the Radiotherapy Support Functions and may take as an input the output produced by the Design Task Functions.
-===== SOBP Dose Functions =====
-Below is a list of the most common sobp dose calculation functions and a brief explanation of their intended usage (Specific details of each function, argument parameters, and return values are provided at the [[http://docs.apps.dotdecimal.com|Dosimetry App Manifest Guide]]).
+===== Dose Functions =====
+Below is a list of the most common PBS and SOBP dose calculation functions and a brief explanation of their intended usage (specific details of each function, argument parameters, and return values are provided at the [[http://docs.apps.dotdecimal.com|Dosimetry App Manifest Guide]]).
+=== PBS Dose Functions ===
+  * **compute_pbs_pb_dose:**
+    * Compute the dose for a PBS field to a list of dose points
+  * **compute_pbs_pb_dij:**
+    * Compute the dose for a PBS field to a list of dose points; this version returns a Dij matrix that captures the individual contributions from every physical PBS spot to every dose point
+  * **compute_pbs_pb_dose_to_grid:**
+    * Compute the dose for a PBS field to a regular dose grid; the result is returned as an image covering that grid
+=== SOBP Dose Functions ===
   * **compute_sobp_pb_dose:**
     * Compute the dose for an SOBP field to a list of dose points
@@ Line 19: / Line 28: @@
     * Computes the PDD for the given machine with the provided parameters
-The result of each of the dose calculation functions is a scalar dose value at each of the prescribed calculation points. The output unit for each function is relative to the units used in the machine calibration during the commissioning process. Note there is a direct one-to-one correspondence between the provided dose calculation points and the resulting dose values (i.e. position within the point position and dose value arrays are consistent).
+The result of each of the dose calculation functions is a scalar dose value at each of the prescribed calculation points (unless otherwise specified). All dose calculation functions require an input "machine model", and the output unit for each function matches the units used in the machine calibration during the commissioning process (additional details on [[dosimetry:commissioning_guide:commissioning_guide|commissioning a machine model can be found here]]) . Note there is a direct one-to-one correspondence between the provided dose calculation points and the resulting dose values (i.e. position within the point position and dose value arrays are consistent).
-==== Dose Calculation Modeling ====
-=== Dose Calculation Method ===
+===== Dose Calculation Modeling =====
+The following general description applies to both PBS and SOBP dose calculations for the Astroid Dosimetry App. Following this general description of the Astroid dose engine, details specific to SOBP calculations will also be provided.
+==== General Dose Calculation Method ====
 Normal use of the dose calculation functions will involve calculation of dose in highly heterogeneous patient geometries. This normal use is usually considered the worst case type of calculation since various size scales and stopping power ranges exist in the computational region, such as small, boney protrusions (head & neck), large bone cross-sections (spine & pelvis), small air cavities (sinus), and large low density regions (lungs). As such, it is important to utilize stable and well trusted computational approaches to dose calculation, such as the Hong model that the Dosimetry App utilizes. The Hong model considers the effects of devices upstream of the patient and the interaction of protons in heterogeneous medium.
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 The analytical model does not “naturally” accommodate the halo protons. These are considered separately as described elsewhere.
-The analytical model thus uses the grid only to compute the proton radiological depth ρ at the geometric location (z) of a point (in the bixel (or beam) coordinate system). The analytical model considers the effect of the range-compensator by reducing the proton range R to R-t and increasing σ by the additional scatter created in the range-compensator material.
+The analytical model thus uses the grid only to compute the proton radiological depth ρ at the geometric location (z) of a point (in the bixel (or beam) coordinate system). The analytical model considers the effect of a range-compensator/shifter by reducing the proton range R to R-t and increasing σ by the additional scatter created in the range-compensator/shifter material.
-Refer to the [[dosimetry:userguide:userguide#known_application_limitations|Known Application Limitations]] that details the limitations of the //Hong et al// calculation method used by the Dosimetry App in respect to heterogeneities and material density. Also, it is expected that the algorithms be utilized only within common clinical range and modulation levels, which at this time include up to about 320mm range and 200mm modulation, and that during commissioning the full range of clinical range/mod pairings be tested to verified correctness for the user defined machine models. Representative dose results for homogeneous tissue are given below to demonstrate the typical accuracy levels expected for this application.
+Refer to the [[dosimetry:userguide:userguide#known_application_limitations|Known Application Limitations]] that details the limitations of the //Hong et al// calculation method used by the Dosimetry App in respect to heterogeneities and material density. Also, it is expected that the algorithms be utilized only within common clinical range and modulation levels, which at this time include up to about 320mm range and 200mm modulation, and that during commissioning the full range of clinical PBS energies and SOBP range/mod pairings be tested to verified correctness for the user defined machine models. Representative dose results for homogeneous tissue are given below to demonstrate the typical accuracy levels expected for this application.
-<WRAP center 85%><imgcaption dpse_accuracy|Representative Dose Calculation Results (R:range, M:mod, I:isocenter depth, D:profile depth)>>{{ dosimetry:userguide:dose_calculation_functions:example-data-accuracy.png?nolink |}}</imgcaption></WRAP>
+<WRAP center 85%><imgcaption dpse_accuracy|Representative SOBP Dose Calculation Results (R:range, M:mod, I:isocenter depth, D:profile depth)>>{{ dosimetry:userguide:dose_calculation_functions:example-data-accuracy.png?nolink |}}</imgcaption></WRAP>
-=== Pristine Peak Modeling ===
+==== SOBP Pristine Peak Modeling ====
 An SOBP calculation yields the dose deposited by a spread-out Bragg peak (SOBP) field. An SOBP field is composed of a set of 1 or more pristine peaks that vary in relative intensity to produce a uniform dose over a longitudinal region. The lateral intensity of each pristine peak of an SOBP field is static and either uniform or Gaussian domed. The SOBP pristine peak data is in the form of a //sobp_calculation_layer// data type in the Dosimetry App.
@@ Line 54: / Line 67: @@
 The pristine peak Ri is a pristine peak depth dose at infinite SAD (i.e. “TMR” like). The depth-dose is directly or indirectly derived from measurements depending on the scattering system.
+==== SOBP Off-Axis Ratios ====
-=== Off-Axis Ratios ===
+The off-axis ratio, OAR, can be (optionally) provided to many of the available SOBP dose calculation functions to allow for improved matching of the results based on the lateral variation of the users actual treatment machine. The OAR is defined as:
-The off-axis ratio, OAR, can be (optionally) provided to many of the available dose calculation functions to allow for improved matching of the results based on the lateral variation of the users actual treatment machine. The OAR is defined as:
 {{ dosimetry:userguide:dose_calculation_functions:oar_equation.png?480 |}}
 where the profile is measured at a fixed plane at position //z// along the beam CAX (with //z=0// at isocenter and positive //z// toward the source) and corrected for measurement in the plane at //z// by projecting back to the isocentric plane and onto a spherical surface with radius //SAD//. The OAR data is provided on a rectilinear grid using an //image// data type. The OAR data is used to scale the initial pencil-beam intensity throughout the field.
-==== Dose calculation point distributions ====
+===== Dose calculation point distributions =====
 For empirical dose calculations, such as described here, the dose is calculated to a point. The dose to a point is assumed to represent the dose within a spatial extent around that point. Gradients in the dose distributions and variable organ sizes necessitate the distribution of points at sufficient resolution to have the dose at the point accurately represent a volume region (typically a rectilinear dose “voxel”) and to represent dose throughout an organ. The user is free to provide lists of points that are distributed within structures, along structure surfaces, or in any other form. The user is responsible to define the computational resolution commensurate with the clinical assessment.